3D landscape real-time imager and corresponding imaging methods

• US 9,560,339 B2
• Filed: 12/21/2011
• Issued: 01/31/2017
• Est. Priority Date: 12/23/2010
• Status: Active Grant

• Current Assignee: Fastree3D SA
• Original Assignee: Fastree3D SA
• Inventors: Borowski, Andr
• Primary Examiner(s): Kelley, Christopher S
• Assistant Examiner(s): Retallick, Kaitlin A
• Application Number:
  US13/995,765
• Publication Number:
  US 20130300840A1
• Time in Patent Office: 1,868 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/483 Details of pulse systems
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects

Abstract

A 3D landscape real-time imager, and method for operating such an imager, where the imager includes:

• • at least one illuminating part which is designed to scan at least a portion of the landscape at a given range and having an ultra-short laser pulse source emitting at least one wavelength, and an optical rotating block, with a vertical axis of rotation, and controlled such that given packets of pulses are shaped in a pattern of rotating beams sent toward the at least partial landscape; and
  • at least one receiving part which includes a set of SPAD detector arrays, each arranged along a vertical direction and rotating at a given speed in synchronism with the optical rotating block of the illuminating part, the detection data of the SPAD detector arrays being combined to acquire 3D imaging data of the at least partial landscape in a central controller.

Claims

1. A 3D real-time landscape imager, comprising:

at least an illuminating part configured to scan at least a portion of the landscape at a given range and having an ultra-short laser pulse source emitting at least one wavelength, and an optical rotating device, with a vertical axis of rotation, and controlled such that packets of pulses are shaped in a pattern of rotating beams sent toward the said at least partial landscape; and

at least a receiving part, which comprises an optical rotating device with a vertical axis of rotation and which rotates in synchronism with the optical rotating device of the illuminating part, said receiving part carrying a set of SPAD (single photon avalanche diode) detector arrays, where the diodes are arranged along the vertical direction,

the receiving part also configured to combine data acquired with the set of SPAD detector arrays according to the various rotations of the two optical rotating devices to obtain 3D images of the said at least partial landscape in a central controller,

wherein the optical rotating device of the illuminating part cooperates with a rotating lens group that comprises multiple lenses, adjusted for various focus and size, to collimate at given vertical angles and/or to control the focus of the illuminating beams at different ranges to the landscape, and

wherein the receiving part further comprises an optical rotating block comprising multiple lenses adjusted for various focus and size for collecting simultaneously light reflected from targets in plural directions, said set of SPAD positioned behind the rotating block.

2. The imager according to claim 1, wherein the optical rotating device of the receiving part comprises additional means for vertical scanning of the landscape and/or vertically stacked sensors to achieve a high vertical resolution.

3. The imager according to claim 1, wherein the ultra-short laser pulse source comprises at least a laser source of pulses, a modulator for removing some generated pulses and for realizing a tagging of packets of pulses, at least an optical amplifier and/or a doped Erbium fiber amplifier.

4. The imager according to claim 1, wherein the optical rotating device of the illuminating part is optically coupled to the ultra-short laser pulse source with an optical joint.

5. The imager according to claim 4, wherein the optical joint comprises a two lenses set, one of which is optically coupled to the output of the ultra-short laser pulse source and the other is coupled to at least a rotating mirror of the optical rotating device of the illuminating part.

6. The imager according to claim 4, wherein the optical joint comprises a cylindrical mirror which is rotary mounted onto a shaft and a set of lenses which are coupled around the cylindrical mirror each onto a branch of an optical fiber from the ultra-short laser pulse source, all the fibre branches running along a glass tube enclosing the optical joint.

7. The imager according to claim 6, wherein the shaft of the rotating mirror is mounted onto an air bearing.

8. The imager according to claim 6, wherein the shaft cooperates with an internal magnet, an external magnet being magnetically linked to provide alignment of the azimuth of the beam with the set of lenses.

9. The imager according to claim 7, wherein the shaft cooperates with an internal magnet, an external magnet being magnetically linked to provide alignment of the azimuth of the beam with the set of lenses.

10. The imager according to claim 1, wherein the optical rotating device of the receiving part comprises alternatively variously shaped rotating polygonal mirror to acquire data on at least a limited part of the 360°

landscape.

11. The imager according to claim 1, wherein the optical rotating block of the illuminating part cooperates with an opto-electrical means as a set of micro-mirror switches to switch the beams on or off synchronously with the scanning of the landscape under a masking controller.

12. The imager according to claim 11, wherein the masking controller cooperates with a fixed laser modulator that handles the distribution of power in a particular angular range.

13. The imager according to claim 1, wherein the optical rotating device of the receiving part comprises means for controlling its rotation synchronously with the optical rotating device of the illuminating part, such that the collected light from the illuminated landscape is accumulated onto a given angle of rotation, with at least a collector comprising lens/detector assemblies with a given angle and/or focus range.

14. The imager according to claim 13, wherein it comprises also a means for control the vertical position of the said at least one collector.

15. The imager according to claim 1, wherein the optical rotating device of the receiving part comprises also alternate 2D image sensors, and is configured to combine 3D data with 2D data acquired in parallel.

16. The imager according to claim 15, wherein the separation of signals for the 2D and the 3D sensors is done by using different wavelengths separated with dichroic filters.

17. The imager according to claim 1, wherein the optical rotating devices of both the illuminating part and the receiving part are combined onto a single shaft driven with a controlled motor, an optical joint with two lenses illuminating a conical mirror with a plurality of lenses which are angularly arranged onto a cylinder affixed onto the said shaft, the lenses transmitting the illuminating beams through an aperture of an enclosure;

a set of receiving lenses, mounted onto the cylinder of the transmitting lenses and sending the laser pulses from the illuminated landscape to a set of SPAD detector arrays.

18. The imager according to claim 17, wherein the SPAD detector arrays are mounted onto the same cylinder rotating onto the single shaft, onto a voice-coil to control a vertical movement up and down of both the conical mirror and of the set of SPAD detector arrays, along their vertical direction aligned onto the central axis of the shaft.

19. The imager according to claim 1, wherein the optical rotating devices of both the illuminating part and the receiving part are common, the common optical rotating device comprising a fast rotating polygonal mirror, the output optical fiber of at least an ultra-short power laser pulsed source being optically coupled to a first lens system which transmits illuminating beams toward a first face of the said fast rotating polygonal mirror, directing it through an aperture of an enclosing box of the imager toward the landscape, a half-silvered mirror being arranged with another face of the said polygonal mirror to direct the reflected light from the landscape toward a first and a second SPAD detector array through their corresponding focus optic, the vertical direction of the two SPAD detector arrays being aligned with the axis of rotation of the said fast rotating mirror, the said rotating mirror being driven with a controlled motor.

20. The imager according to claim 19, wherein the two SPAD detector arrays are arranged one above the other in the vertical direction.

21. The imager according to claim 1, wherein it comprises a means for optical multiplexing to enlarge the possibilities of the 3D real-time landscape imager which comprises partially reflecting mirrors in the optical path to let the landscape imager of acquiring 3D data in several directions at the same time.

22. The imager according to claim 21, wherein the partially reflective mirrors have various reflecting shapes comprising:

stripes, angled stripes, squares and/or a plurality of curved shapes stacked on top of each other on the same mirror axis.

23. The imager according to claim 1, wherein a RF wireless or optical link is used for bringing power and data to the sensors of the collectors onto the optical rotating device of the receiving part.

24. The imager according to claim 1, further comprising air bearings.

25. The imager according to claim 1, wherein the imager is at least partially enclosed in a sealed enclosure, possibly over-pressured with a neutral gas.

26. The imager according to claim 1, wherein the optical rotating device is rotated onto a motor which is controlled with a PLL designed to speed control with a low jitter single reference point for lowering the mechanical jitter of the optical rotating devices.

27. The imager according to claim 1, wherein further comprising a safety mechanism.

28. The imager according to claim 1, wherein the data detected at the SPAD detector arrays and/or at auxiliary 2D sensors are combined at a means for generating received data, intensity information is combined with the 3D coordinates of each voxel of a 3D representation of the illuminated landscape and such a representation is used onto a 3D display, a 2D display with a graphical unit interface to select a point of view and/or a projection plane, or also a 3D meshed representation useful in a CAD environment.

29. The imager according to claim 1, wherein it comprises at least a local electronic controller supervising the real-time operation of the 3D real-time landscape imager.

30. A set of 3D real-time landscape imagers comprising 3D real-time landscape imagers which comprise:

at least an illuminating part which is designed to scan at least a portion of the landscape at a given range and having an ultra-short laser pulse source emitting at least one wavelength, and an optical rotating device, with a vertical axis of rotation, and controlled such that packets of pulses are shaped in a pattern of rotating beams sent toward the said at least partial landscape;

at least a receiving part which comprises an optical rotating device with a vertical axis of rotation and which rotates in synchronism with the optical rotating device of the illuminating part, said optical rotating device carrying a set of SPAD (single photon avalanche diode) detector arrays, where the diodes are arranged along the vertical direction, and the optical rotating device of the receiving part is rotating in synchronism with the optical rotating device of the illuminating part, the receiving part configured to combine data acquired with the set of SPAD detector arrays according to the various rotations of the two optical rotating devices to obtain 3D images of the said at least partial landscape in a central controller,

wherein said set of 3D real-time landscape imagers comprises a central controller and a high-speed data link for communication of data streams between them and their central controller such that the 3D landscape imagers coordinate their “

launching pulse agenda”

to avoid simultaneous pulse reflection from the same targets points, and

wherein the optical rotating device of the illuminating part cooperates with a rotating lens group that comprises multiple lenses, adjusted for various focus and size, to collimate at given vertical angles and/or to control the focus of the illuminating beams at different ranges to the landscape, and

wherein the receiving part further comprises an optical rotating block comprising multiple lenses adjusted for various focus and size for collecting simultaneously light reflected from targets in plural directions, said set of SPAD positioned behind the rotating block.

31. The set of 3D real-time landscape imagers according to claim 30, wherein the central controller of the set of cooperating 3D real-time landscape imagers comprises a means for controlling the illuminators of the connected 3D landscape imagers which generate tagged packets of laser pulses, and a means for selecting corresponding reflected packets of pulses from each receiver of the cooperating 3D real-time landscape imagers, the central controller configured to combine the 3D data produced at each 3D real-time landscape imager of the set and for producing a global 3D image from the cooperating 3D real-time landscape imagers on the basis of the various positions and orientations of the cooperating 3D landscape imagers.

32. The set of 3D real-time landscape imagers according to claim 31, wherein the central controller comprises a means for implementing of a rough, optically coupled, cooperation protocol using tagged packets of illuminating pulses from each 3D real-time landscape imager.

33. A method of operating a 3D real-time landscape imager, said 3D real-time landscape imager comprising:

at least an illuminating part which is designed to scan at least a portion of the landscape at a given range and having an ultra-short laser pulse source emitting at least one wavelength, and an optical rotating device, with a vertical axis of rotation, and controlled such that packets of pulses are shaped in a pattern of rotating beams sent toward the said at least partial landscape; and

at least a receiving part which comprises an optical rotating device, with a vertical axis of rotation and which rotates in synchronism with the optical rotating device of the illuminating part, said optical rotating device carrying a set of SPAD (single photon avalanche diode) detector arrays, where the diodes are arranged along the vertical direction, and the optical rotating device of the receiving part is rotating in synchronism with the optical rotating device of the illuminating part, the receiving part configured to combine data acquired with the set of SPAD detector arrays according to the various rotations of the two optical rotating devices to obtain 3D images of the said at least partial landscape in a central controller,

wherein said method of operating said 3D real-time landscape imager comprises;

emitting at least a series of ultra-short power laser pulses of at least a given wavelength, at a given frequency;

forming the said series of pulses into a plurality of beams which are sent to at least a given area of the landscape with at least a given longitudinal focus position;

reflecting said formed beams of pulses from the landscape; and

receiving said reflected pulses onto at least a SPAD detector array, said SPAD detector arrays rotating in synchronism with the emission of said illuminating beams and being arranged to produce detected data on the basis of the knowledge of the round trip delay of the pulses and using the timing coherence of the pulse train for efficiently detecting signals at each SPAD detector cell of the said SPAD detector arrays; and

processing said detected data to obtain 3D image data, and

wherein the optical rotating device of the illuminating part cooperates with a rotating lens group that comprises multiple lenses, adjusted for various focus and size, to collimate at given vertical angles and/or to control the focus of the illuminating beams at different ranges to the landscape, and

wherein the receiving part further comprises an optical rotating block comprising multiple lenses adjusted for various focus and size for collecting simultaneously light reflected from targets in plural directions, said set of SPAD positioned behind the rotating block.

34. The method according to claim 33, wherein, in acquiring 3D data on the 360°

landscape around at least a 3D landscape imager very quickly, it comprises a step of acquiring quasi-simultaneously 3D data on the same landscape at different focus by means of rotating parallel sensors and optics, and a step of combining generally those 3D data in a single landscape unified description.

35. The method according to claim 34, wherein it comprises a step of beaming, in quickly rotating sequences, vertical lines of very high peak power, ultra short, ultrahigh peak power IR-light pulse trains on the landscape 3D relief lines and capturing efficiently the reflected lines of photons on ultra-fast in-line equivalent arrays of SPAD sensors at GHz frequency.

36. The method according to claim 33, wherein the step of receiving reflected pulses comprises the step of receiving the reflected light through the use of shaped diffuser on top of the SPAD detectors.